A massive British Airways technology outage that stranded 75,000 passengers over the weekend will cost the airline at least $68 million, according to an estimate from Flightright.com.

The estimate is based on roughly 800 flights cancellations at Gatwick and Heathrow on Saturday and Sunday and associated EU rules to compensation stranded travelers, Reuters reported.

The outage involved a power surge on Saturday morning that hit BA’s flight, baggage and communication systems, the report said. It was so strong it also rendered the back-up systems ineffective, Reuters added.

British Airways CEO Alex Cruz Responds

Chairman and CEO Alex Cruz discussed the outage in this video:

The company followed up with this video on May 29:

Most reports have dismissed terrorism as a possible cause for the outage. But cybersecurity experts have been watching the story closely for potential signs of cyber terrorism that somehow triggered the power surge.

Power Surges and IT Attacks?

On a much smaller scale, security experts have been worried about so-called “USB Killer” devices. Once connected, the USB device sends high-voltage negative DC through a USB port until it fries the circuitry of the host device, Tom’s Hardware reported in September 2016.

Or as Fortune put it…

“When plugged into any device, The USB Killer, released earlier this summer, rapidly draws power from the hardware, then returns that power in an overloading burst. According to the makers, this “instantly and permanently disables unprotected hardware.” Potential targets include not just PCs, but TVs, copy machines—anything with a USB port.”

So. What actually caused the power surge that impacted British Airways? Hmmm….